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This article in JEQ

  1. Vol. 42 No. 4, p. 1245-1255
    Received: Dec 4, 2012
    Published: June 24, 2014

    * Corresponding author(s): gnoe@usgs.gov


Hydrologic Connectivity to Streams Increases Nitrogen and Phosphorus Inputs and Cycling in Soils of Created and Natural Floodplain Wetlands

  1. Kristin L. Wolfabc,
  2. Gregory B. Noe *a and
  3. Changwoo Ahnb
  1. a National Research Program, U.S. Geological Survey, 430 National Center, Reston, VA 20192
    b Dep. of Environmental Science and Policy, George Mason Univ., 4400 University Drive, Fairfax, VA 22030
    c current address, Champlain College, 163 South Willard, Burlington, VT 05401


Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots (n = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

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Copyright © 2013. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.